This invention relates to a novel aqueous fluid rheology or flow modifier composition and a method for producing same. These high molecular weight, water soluble polymers contain both water soluble and water insoluble monomers. The water soluble monomers are acrylamide (AM) and a salt of acrylic acid (H), and the water insoluble monomer is a higher alkylacrylamide (R). These polymers will be hereinafter referred to as HRAM. The process for their preparation relies on solubilizing the water insoluble monomer into an aqueous micellar solution containing one or more surfactants and the water soluble monomer(s). Charged groups are incorporated in these polymers by copolymerization with acrylic acid or an alkali metal acrylate, or by post-hydrolysis of some of the acrylamide units using an alkali hydroxide, such as sodium hydroxide. Aqueous solutions of these hydrophobically associating polymers exhibit enhanced viscosification, reduced salt sensitivity and other desirable rheological properties found useful in a variety of applications.